BiO/BiO Nanoheterojunction for Highly Efficient Electrocatalytic CO Reduction to Formate.

Heterostructure engineering plays a vital role in regulating the material interface, thus boosting the electron transportation pathway in advanced catalysis. Herein, a novel BiO/BiO heterojunction catalyst was synthesized via a molten alkali-assisted dealumination strategy and exhibited rich structural dynamics for an electrocatalytic CO reduction reaction (ECORR). By coupling in situ X-ray diffraction and Raman spectroscopy measurements, we found that the as-synthesized BiO/BiO heterostructure can be transformed into a novel Bi/BiO Mott-Schottky heterostructure, leading to enhanced adsorption performance for CO and *OCHO intermediates. Consequently, high selectivity toward formate larger than 95% was rendered in a wide potential window along with an optimum partial current density of -111.42 mA cm that benchmarked with the state-of-the-art Bi-based ECORR catalysts. This work reports the construction and fruitful structural dynamic insights of a novel heterojunction electrocatalyst for ECORR, which paves the way for the rational design of efficient heterojunction electrocatalysts for ECORR and beyond.